stands for Mint
State and 69 is a
grade number on a
scale of 1 to 70.
Mint state coins are
coins in the same
condition that they
were in just after
leaving the mint,
with no evidence of
wear or handling.
Mint state coins can still have normal damage from being put in hoppers and bagged, so the degree of damage is evaluated by the number associated with the letter grade. An MS-60 would be the lowest grade of mint state coin, with no wear or handling but numerous "dings", etc. from the minting process. An MS-69 coin would have essentially no evidence of such damage, and be in pristine condition. Assigning a grade that high is a job reserved for trained experts who could recognize and evaluate even the slightest flaws.
Grading coins is an art. Some would have you believe that it is a science, but it is an art that requires some skill. That being said, anyone with one good eye can get a fairly good idea as to the neighborhood of the grade of a coin. It's important to know the grade of a coin because, in general, the higher the grade of a coin, the higher its price.
The MS Grading Chart
MS70 - PERFECT COIN; No imperfections under 20x magnification; full strike; No minting made imperfections; 100% full dynamic luster; no contact marks or hairlines visible under 20x magnification.
MS69 - these coins are coins that exhibit imperfections under magnification higher than 10x; one or 2 imperfections allowed no more; luster and eye appeal must be the same as a MS70
MS68 - must appear perfect under 10x magnification with the exception of a nearly imperceptible scratch, nick or flaw in a non-focal area of the coin.
MS67 - maximum of 2 imperfections under 5x magnification.
MS66 - Intermediate grade where a coin may have MS67 surface preservation but MS65 luster would then qualify for a MS66 grade.
MS65 - Minor imperfections under 5x magnification but not more than 5 or 6; Full strike and full luster; overall pleasing appearance.
MS64 - Intermediate grade where a coin is decidedly better than a MS63 but not deserving of a MS65 grade; usually a coin that looks like an MS65 until inspected under 5x magnification.
MS63 - Noticeable marks without magnification; toning may not be visually appealing; possibly not a full strike.
MS62 - Above average mint state example and should have MS63 qualities except to a lesser degree in so far as surface preservation & mint bloom is concerned; abrasions &/or scratches should not overwhelm the grader.
MS61 - No wear but scratches, abrasions, and other imperfections are evident; dull lustre and unattractive toning; no obvious scratch or gash making such the focus of the coin.
MS60 - No wear but scratches, abrasions, and other imperfections are evident to the naked eye & fairly abundant; dull lustre and unattractive toning; may have one or two major detractions which just fall short of being deemed a damaged no grade.